1. Field of the Invention
The present invention relates to a dynamic speaker, and particularly to a structure for supporting a diaphragm with a frame.
2. Description of the Related Art
As one type of a speaker, a dynamic speaker has been known heretofore. The dynamic speaker, as disclosed in, for example, JP-A-6-178390, comprises a diaphragm on which a voice coil is fixed and a frame for supporting the outer periphery of the diaphragm.
As disclosed in the publication, there is a well-known support structure, for supporting the diaphragm with the frame, that the outer periphery of the diaphragm is adhered and fixed to the frame.
However, simply adhereing and fixing the diaphragm to the frame does not provide the sufficiently reliable support structure for the diaphragm, and risk remains of the diaphragm separating from the frame during the use of the speaker. This is particularly true when the speaker is mounted in an automobile, etc. where the speaker is subject to much shock and impact load that makes the separation of the diaphragm even more likely.
Furthermore, since the speaker with the diaphragm that is attached to the frame with the adhesive requires application of the adhesive during manufacturing, the automation of the speaker manufacturing process is made difficult and is further complicated by adjusting the viscosity of the adhesives and implementing the drying process following the application of the adhesives.
An object of the present invention which has been made in light of the aforementioned problems is to provide a sure method for the prevention of the separation of the diaphragm from its frame and to simplify the speaker manufacturing process and promote its automation.
In the present invention, the object is achieved by use of a caulking structure as a support structure for supporting the diaphragm with the frame.
According to the present invention, there is provided a speaker comprising:
a diaphragm;
a magnetic circuit unit defining a cylindrical magnetic gap;
a voice coil having a first portion fixed to the diaphragm and a second portion placed in the cylindrical magnetic gap; and
a frame for supporting the outer periphery of the diaphragm,
wherein the frame comprises an annular ring formed along with the shape of the outer periphery of the diaphragm and a mounting portion extending radially outward from the magnetic circuit unit; and
the ring and the mounting portion are caulked-jointed to each other with the diaphragm clamped therebetween.
No particular restrictions on the material used, shape and the like are imposed on the specific construction of the xe2x80x9cdiaphragm,xe2x80x9d xe2x80x9cvoice coilxe2x80x9d or xe2x80x9cmagnetic circuit unitxe2x80x9d so long as they can be used as constituent elements of the dynamic speaker.
No particular restrictions on the material used, shape and the like are imposed on the specific construction of the xe2x80x9cringxe2x80x9d or xe2x80x9cmounting portionxe2x80x9d so long as both can be caulked together. Furthermore, the xe2x80x9cmounting portionxe2x80x9d may be separately formed or integrally formed as a constituent element of the magnetic circuit unit.
No particular restrictions are imposed on the specific method of the caulking. The methods that can be used include, for example, a cold caulking or caulking that uses thermal deformation induced by ultrasonic vibrations. Furthermore, caulking portions subject to plastic deformation may be formed either on only the ring or the mounting portion, or both.
As the afore-described construction shows, the speaker of the present,invention comprises a diaphragm which is supported by its outer periphery by a frame which comprises a ringxe2x80x94formed in an annulus following the outer peripheral shape of the diaphragmxe2x80x94that is connected to a mounting portion that extends radially outward from a magnetic circuit unit. The functions and effects described hereinbelow are obtained as a result of the caulked-joint of the ring and the mounting portion with the diaphragm clamped therebetween.
Since the diaphragm is clamped between the ring and the mounting portion which are caulked-jointed to each other the supporting strength offered by the frame to the diaphragm is significantly increased as compared to the conventional technique attaching the diaphragm to the frame using only an adhesive. This reliably prevents the diaphragm from separating from the frame during the use of the speaker.
Furthermore, since the task of applying the adhesives required with the conventional techniques is eliminated in this invention, automation of the speaker fabrication process is facilitated. Moreover, the process of adjusting the viscosity of the adhesives or drying the adhesives after their application is eliminated, further simplifying the speaker manufacturing process.
In the foregoing manner, the present invention reliably prevents the separation of the diaphragm from the frame, and promotes and facilitates the automation of the speaker manufacturing process.
Even though in the afore-described construction the diaphragm is simply clamped between the ring and the mounting portion which are caulked-jointed together, there is no risk of an acoustically detrimental deformation of the diaphragm arising from the use of the caulking construction since the diaphragm itself plays no role in the caulked-joint.
As stated previously, no restrictions are imposed on the specific caulking method. Since at least either the ring or the mounting portion is constructed of synthetic resin with a plurality of caulking portions 30bxe2x80x2 which are then thermally deformed by exposure to ultrasonic vibrations, the caulked-joint can be easily and securely performed even if the speaker were to be small with the extremely small caulking portions provided on the ring or the mounting portion.
Since the ultrasonic vibrations are used for the thermal deformation of the caulking portions without a need for an ultrasonic welding of the ring and the mounting portion, there is no need to give any consideration to the welding compatibility of the materials used for the two pieces. This means that the use of a thermal deformation induced by exposure to ultrasonic vibrations imposes no limitations on the degree of freedom in the selection of the materials to be used for the ring and the mounting portion. Needless to say, the degree of freedom in the selection of the material for the diaphragm is not restricted in anyway since the diaphragm plays no role in the caulked-joint.
In addition to the afore-described construction, the following effects and function are obtained if the ring is caulked-jointed to the diaphragm by the plastic deformation of the caulking portions formed on the ring.
The ring is temporarily fixed to the diaphragm before the ring and the mounting portion are caulked-jointed. This allows the diaphragm to be positioned at its predetermined position when it is clamped down by the caulking of the two pieces. If the caulking is used for the temporary attachment, the diaphragm can be positioned without impeding the automation or the simplification of the speaker manufacturing process.
Moreover, since the plastic deformation of the ring 30 is accomplished by the thermal deformation of the caulking portions 30dxe2x80x2 on the ring 30 by their exposure to ultrasonic vibrations, the same effects and functions are obtained as provided with the use of ultrasonic vibrations for the caulked-joint of the ring and the mounting portion.
Furthermore, the following functions and effects are obtained if, in the construction described above, at least either the ring or the mounting portion is formed with circumferential direction positioning piece which determines the circumferential positioning of the ring and the mounting portion.
The mounting portion must be provided with openings for lead wires so that the lead wires of the voice coil that is attached to the diaphragm may be connected to the terminals. The caulked-joint of the ring and the mounting portion must be done at angular positions that are different from where the lead wires will be drawn out. If the afore-described circumferential direction positioning piece is formed to position the ring and the mounting portion in the circumferential direction, the caulked-joint of the two pieces can be reliably done at the prescribed angular positions. In particular, since, if the ring is caulked to the diaphragm in advance, the caulked-joint of the ring and the mounting portion must be done at angular positions that are different from where the ring is caulked to the diaphragm, the formation of the afore-described circumferential direction locating piece is particularly effective.
Incidentally, if the afore-described construction of temporarily fixing the ring by the caulking is used (that is, the caulking of the ring to the diaphragm by the plastic deformation of the caulking portions which are formed on the ring), the diaphragm will be clamped at the right position between the ring and the mounting portion regardless of whether the ring and the mounting portion in jointed by caulking or otherwise (for example by an adhesive).
Furthermore in this case, the same functions and effects are obtained if, instead of the ring being temporarily fixed by caulking, the mounting portion is temporarily fixed by caulking (that is, the caulking of the mounting portion to the diaphragm by the plastic deformation of the protrusions which are formed on the mounting portion).